Adjective- describing someone or something that is mischievous, or up to shenanigans or tomfoolery; acting as a deviant, jokester, trickster; one who joshes around or engages in ballyhoo; rascal-like (mild sass optional)

As a child, young Charles was well-behaved, polite, and followed all the rules; however, as he grew up, he became awnry.